Probes are used as interconnects for providing electrical communication between a device under test (DUT) and a testing apparatus. Conventional probes are typically formed from a base material, such as beryllium-copper (Be—Cu), and have one or more outer layers formed on the base material. In some cases, no plating is applied to the probes. Those outer layers of plating when applied have included, for example, plated layers of nickel, gold, or rhodium and palladium (with or without cobalt). The outer layers have generally been added to increase the hardness and decrease wear of the probe. The increased hardness is typically provided to break through an oxide layer that forms on the contact pads being tested. The oxide layer adversely affects the electrical conductivity between the pad or bump and the probe and, thus, it is desirable for the probe to pierce the oxide layer in order to achieve an improved electrical connection.
In certain conventional probes, the outer plating layers have been formed on the entire probe. This has several drawbacks. First, coating the entire probe is costly. Second, the plating on the probe can negatively affect the mechanical characteristics of the probe and, in particular, the spring characteristics of the probe. Third, a very hard coating on the spring part/section of the probe may peel off during cycling operation of a probe.
Thus, it would be desirable to provide an improved plated probe which is less expensive to manufacture and provides increase durability, while minimizing alterations in the probe spring characteristics.